Method and apparatus for electrolytic treatment of slide fasteners



April 30, 1957 Filed July 29, 1952 c. c. COHN 2,790,756 METHOD ANDARATUS F0 LE owns TREATM OF suns TE s 2 Sheets-Sheet 1 XVAVA AVAV V l 2a7 ""l Ji .x

mmv FIG. 3 CHARLES C. CO

ATTORNEYS April 30, 1957 2,790,756

C. C. COHN METHOD AND APPARATUS FOR ELECTROLYTIC TREATMENT OF SLIDEFASTENERS Filed July 29, 1952 -2 Sheets-Sheet 2 INVENTOR. CHARLES c.COHN ATTORNEYS United States Patent ice METHoD AND APPARATUS FORELECTROLYTIC TREATMENT OF SLIDE FASTENERS Charles C. (John, AtlanticCity, N. 3.

Application July 29, 1952, Serial No. 301,509 2 Claims. (Cl. 204-23 Thisinvention relates to methods and apparatus for the electrolytictreatment of elements of slide fasteners of the zipper type, thetreatment referred to including electroplating, anodizing of aluminumelements, or the like. trolytic treatment of slide fasteners in closedform and in long strips, the treatment being of a continuous nature.

From the following description, it will be evident that the invention isapplicable to the electrolytic treatment of such fasteners in general,but to simplify the description, stressv will be particularly laid onthe anodizing of aluminum or aluminum alloy elements, the handling ofthe elements evidently being applicable to treatment such aelectroplating.

For many uses, particularly in clothing, the natural color of the metalfrom which the zipper elements are formed is objectionable, and,consequently, it has been generally customary to provide covering flapsfor zlppers to hide the elements from view. These flaps, however, are

not always desirable and in many instances a better appearance of theproduct would result if the zipper elements, though exposed to view,were colored either to match the adjacent fabric or to contrast with itto provide ornamentation. Various methods of coloring or attempting tocolorelements have been used. For example, they exposed portions [ofzipper elements have been painted. When a garment having painted zippersis sold the ap pearance may be quite attractive; but in use the paintvery readily becomes dislodged and the irregular exposure of bare metaldetracts greatly from the appearance of the.

garment. It has been recognized that a quite superior colored surfacefrom the standpoint of resistance to wear could be produced if zipperelements were made of alumiham or its alloys and the exposed surfaceswere oxide coated and then dyed. In particular, if this oxide coatingwas formed by anodizing the colored oxide coating, being extremely hard,would be quite resistant to wear.

While the desirability of providing colored aluminum In the case of aclosed zipper, it might appear that all' of the zipper elements are inseries contact and that, consequently, it would be possible to secureelectrical connection-with all of the elements by connection with anelectrical current source at one end of the strip. however, this is notthe case at least to the extent of providing sufiiciently goodelectrical contact to insure the proper carrying of current withsubstantially negligible resistance through any considerable length ofthe strips.

In'par-ticular, anodizing of aluminum zipper elements re-" The inventionhas particular reference to the elec-.

In fact,

p 2,790,756 Patented Apr. 30, 1957 quires relatively heavy currents andthe resistance, due to poor contacts, would cause a very rapid fallingoff of voltage along the zipper. In accordance with my Patent No.2,572,838, dated October 30, 1951, there is provided a method for theelectrolytic treatment of zippers involving the securing of goodelectrical contacts between the elements of a closed zipper by impartinga sinuous form thereto which insures tight electrical engagement at theprojections and sockets of the zipper elements. The method disclosed insaid patent is, however, adaptable only to the anodizing or otherelectrolytic treatment of finite lengths of zippers inasmuch as thesinuous configuration can be achieved satisfactorily only through rack-Various other methods for the anodizing or other electrolytic treatmentof zippers have been proposed but these generally involve special zipperconstructions or the use of special apparatus for forming or handlingthe zipper elements. In my Patent No. 2,596,888, dated May 13, 1952there is disclosed a method involving the preliminary treatment of ashaped wire from which the zipper elements are formed. It is, however,from the standpoint of simplicity of production, desirable to effect theelectrolytic treatment on a finished closed zipper and, in particular,this is desirable when the zipper elements and the carrying tape are tobe given the same color. This is possible in the case of anodizedaluminum zipper elements,

when the completed closed zipper may be subjected to dyeing which willcolor not only the anodized coatings of the elements but the carryingtapes as well.

The general object of the present invention, therefore, is to provide amethod and apparatus for the electrolytic treatment of closed zipperswhich, in the case of anodizing of aluminum zipper elements may befollowed by dyeing. In accordance with the invention, and withoutdetriment to the zippers, good electrical contacts between the zipperelements are secured resulting in the possibility of handling closedzippers continuously in substantially the same fashion as one mighthandle a wire in electrolytic treatrnent thereof. This general object ofthe invention and more detailed objects thereof will become apparentfrom the following description read in conjunction with the accompanyingdrawing, in which:

Figure'l is a diagrammatic sectional view showing the preliminarytreatment of a closed zipper to effect good electrical contact betweenthe elements thereof;

Figure 2 is a transverse sectional view showing the same matter asFigure 1;

'Figure 3 is an enlarged sectional view showing analternativearrangement and procedure for securing good electrical contact betweenthe elements of a closed zipper;

Figure 4 is a sectional diagram showing a type of electrolytic procedurewhich may be carried out as a con tinuous process; and

Figure 5 is a sectional diagram showing an alternative type ofelectrolytic procedure carried out as a continuous process.

The nature of the invention may be briefly described by stating that itinvolves a slight distortion of the interengaging portions of theelements of a closed zipper to' provide tight electrical contact. Aswill appear hereafter, this probably takes advantage of the resistanceof the relatively inelastic supporting tapes to extension in the Thezipper elements contain all of the elements are thus treated, theaggregate tendency to increase the effective length of the assembly ofzipper elements at their regions of interengagement is resisted by theinelastic carrying tape and, consequently, the elements are held tightlytogether under a sort of spring action which is found to be suflicientto. provide good electrical contact and low resistance through a longlength of a closed zipper so treated. It then follows that by makingelectrical contacts at only spaced points good electrical connectionsare provided throughout considerable lengths of a continuous length ofzipper so that electrolytic treatment may be satisfactorily effected.

Referring first particularly to Figures l and 2, there is indicatedgenerally by the numeral 2 a closed zipper which may be of conventionaltype as generally produced and sold. Such a zipper comprises a pair ofsubstantially inelastic tapes 4 which are beaded at their edges 6 alongwhich there are clamped the zipper elements 8. Each of these elementscomprises a projection 10 and a socket 12 (shown in Figure 3); Theprojections and sockets aresimultaneously formed in the zipperelementsby a punching procedure and it will be found on microscopicexamination of zipper elements that while theseprojections and socketsare not well defined as to shape they are both of tape-red pyramidalform with their edges and corners generally somewhat rounded andirregular. In any event, however, the projection is essentially taperedand thisis also true of the socket.

As manufactured, even though the elements on the two tapes areinterlocked, it is found that the electrical contacts between them arequite irregular so that electrical continuity seldom extends along thezipper for more than the space occupied by a few elements.

It might be thought, on casual consideration, that nevertheless if thezipper was drawn along a conducting electrode in flat form there wouldbe produced sufficiently good continuous electrical contact between theelements and the electrode to provide the necessary connections foranodizing or other electrolytic treatment. This, however, is not thecase, and the reason is evident upon microscopic inspection of a typicalzipper. The zipper elements are not of uniform dimensions, andobviously, therefore, those which extend to a maximum extent from thetapes will prevent engagement of intermediate elements with theelectrode. It is accordingly essential that current should be conductedbetween adjacent elements throughout considerable lengths of thezippers.

It has been proposed that tapes carrying zipper elements might bepressed against a conducting metallic tape by a felt strip saturatedwith an electrolyte and thus, by individual pressure on each elementcontact thereof with the metallic tape might be assured. This method,however, is unsatisfactory because the felt strip prevents free escapeof gas and accumulation of gas interrupts flow of current. It isessential that freedom of gas removal be afforded and this is the caseinmy procedure.

In accordance with the present invention, referring particularly toFigure 2, the zipper is passed between a pair of rollers 14 and 16 whichare of similar type providing cylindrical portions 18 arranged to clampand feed the tapes of the zipper strip, one or both of the rollers beingdriven at suitable speed. The rollers are grooved as indicated at 20 soas to clear the outer surfaces of the zipper elements, but desirably soas to engage the ends of the elements which grip the tape to maintainthe assembly of elements passing between the central portions of therollers. The rollers are provided with outwardly projecting ribs 22arranged to engage and compress the zipper elements exteriorly of thesockets 12. The clearances between the ribs 22 are less than theoriginal thickness of the zipper elements so that the walls outside thesockets 12 are pressed inwardly. As a result, and due to the taperedforms of the sockets and projections, a wedging action occurs tending tomove the adjacent elements apart in the longitudinal direction of thestrip. This tendency to move apart is resisted by the inelastic tapesand the result is that the projections are held in the sockets in ayielding fashion but sufficiently tightly to maintain good electricalcontact. Some swaging action may also occur tending to extend the wallsof the sockets towards the roots of the projections.

While the zipper elements are thus slightly distorted from theiroriginal shapes, the amount of distortion necessary to secure goodelectrical contact between adjacent elements is not detrimental to theproper eventual operation of the zipper for opening and closing underthe action of the usual slide. This is apparently due to the fact thatthe distortion is transverse to the faces of the tapes whereas theopening and closing motions are in directions in the plane of the tapes.Of course, excessive distortion should be avoided, the ribs 22 beingspaced to secure only that distortion which is necessary to provideelectrical continuity either when the tape is straight or, as willappear hereafter, when the tape is given a suitable radius of curvature.

Instead of providing continuous swaging or compres sing ribs such as at22 in Figure 2, the compressing or swaging action may be localized asindicated in Figure 3 by providing about the circumferential positioncorresponding to the rib 22 small teeth 28 which are adapted to engagethe zipper elements only adjacent to the walls at the open ends of thesockets 12. The distortion is thus localized without compression of theother portions of the zipper elements. In order to provide for properpositioning of the teeth 28 with respect to the zipper elements, one orboth of the rollers 24 and 26 may be pr0- vided with teeth 30 engageablebetween the zipper elements attached to one of the tapes. In otherwords, the teeth 30 engage between alternate zipper elements of theseries and serve to maintain definite circumferential relationshipsbetween the zipper and the rollers. The rollers, of course, may begeared together so that teeth on only one and on only one side of thezipper will suffice.

The electrolytic treatment of the zipper provided in accordance with theforegoing is illustrated in Figure 4. A suitable tank 32 contains anelectrolyte 34. The zipper 2 enters the tank guided about a roller 36therein and leaves the tank guided about a roller 38. The zipper maypass from a supply reel 37 and be wound up upon a receiving reel 39. Thereceiving reel will be driven at a suitable rate of speed to providesufiicient time in the bath for the electrolytic action to take place oneach zipper element. Before passing to the receiving reel the zippermay, if desired, pass through a rinsing bath to remove the electrolyte.Between the rollers 36 and 38 there is a curved electrode plate 40 overwhich the tape passes with scraping contact. A second electrode isindicated at 42, andconnections are made to terminals 44 which may besupplied with alternating or direct current in accordance with theelectrolytic treatment involved. In passing over the electrode plate 40,some of the zipper elements will have actual rubbing contact therewithand will serve to receive the current which will then be distributed tothe elements which may not make contact with the plate through theconductive path afforded be tween the elements as above described. Arubbing or scraping contact with the plate 40 is maintained which isparticularly important in the case of anodizing to prevent the formationof a non-conductive oxide coating on the plate 40 which will be ofaluminum or aluminum alloy. Under the conditions indicated, theelectrolytic treatment will, of course, occur completely only on oneface of the zipper with less complete treatment. on the other. However,generally, this is all that is required, there being completely treatedthe surface of the zipper which will be in view in its final use. It istherefore, generally immaterial that one side of the zipper will beuntreated or substantially so. It will, of course, be evident that inpractice there will be a number-of zipper strips running side by sidethrough the electrolytic tank for simultaneous treatment. I g

It will be noted that the face of the zipper undergoing electrolytictreatment is free of obstruction to gas removal so that bubbles may formand escape, avoiding polarization or interruption of current flow.

Figure shows an alternative electrolytic process which may be carriedout in accordance with the invention. A tank 46 contains an electrolyte47 in which is immersed a rotor 48 mounted on a rotating shaft 50, therotor carrying at its periphery axially extending rods 52 giving rise toa squirrel cage formation, the entire rotor being metallic. A closedzipper 54, the elements of which are compressed or distorted asdescribed above, or which are formed originally, to insure properconductivity between them when the zipper is distorted to proper radiiof curvature, is fed past a guide roller 56 and a reciprocating plunger58 timed with respect to movement of the rotor to project bights betweenpairs of rods 52 as indicated at 60. These bights are frictionally heldbetween the rods and are carried about by the rotor through the bath,being finally stripped from the rotor :at the postion of guide roller62. The rotor 50 is con- .nected to one of a pair of current inputterminals 64, the other of which is connected to an electrode 66 in thecase of direct or pulsating current anodizing or electroplating, or,desirably to a second rotor assembly in the case of alternating currentanodizing.

In the operation of this process, certain elements of the zipper makeactual metallic contact with the rods :52 while current is conducted tothe intermediate elements by the serial contacts thereof. If large loopsor bights 60 are formed, the zippers treated will usually requirepreliminary distortion as described above to insure good inter-elementconduction; but if small loops are provided betweenclosely spaced bars52 such preliminary treatment may be unnecessary. Specially formedzippers having good inter-element conduction need not be preliminarilytreated. It will be evident that with conduction provided as justindicated proper electrolytic treatment will result.

In the case of anodizing, when oxide coatings will be formed on the rods52, which will be of aluminum or aluminum alloy, cleaning of the oxidecoatings from the rods will be effected when the bights are formed byplunger 58, the incoming portions of the zipper scraping the rods arethereby cleaning the same.

Obviously, when the rotor is of suitable axial extent many zippers maybe fed thereto and carried thereby in parallel.

The particular treatment involved depends entirely upon the resultsdesired and need not be detailed, reference being made to thediscussions of suitable baths, dye procedures and sealing procedures setforth in my patents mentioned above, any of which are herein applicable.As therein pointed out, when anodizing of aluminum zipper elements isbeing efiected followed by dyeing, the cotton tapes may besimultaneously dyed, or, alternatively, the cotton tapes may be pre-dyedor subsequently dyed in contrasting colors or with different types ofdyes even in substantially the same colors as the zipper elements.

Desirably in a continuous anodizing process such as any herein describedthere is used a type of bath which will effect anodizing in a minimum oftime, utilizing high current densities, so that the progress of thetapes may be speeded up consistently with having each element subject tothe anodizing action for a suflicient period to secure the desiredthickness and type of coating. Sulfuric acid electrolytes are suitablefor such anodizing utilizing direct or alternating current, in whichcase both electrodes 40 and 42 may be of aluminum. Alternatively, ifalternating current anodizing is effected, there may be two sets ofzippersin the bath, both. moving along and in contact with electrodemembers such'as 40, the two electrodes being connected to the terminalsof the alternating current supply. Numerous anodizing procedures ofknown types may be used and consequently need not be specificallydescribed.

It will be evident that electroplating may be effected in the samegeneral fashion using, of course, direct current. In the case ofelectroplating with a metal, the conductivity of the plated surface willnot be reduced by the plating operation and it is, therefore, possibleto invert the tape in a second path through the bath with its originallyplated surface in contact with an electrode to secure plating of theother side of the zipper. As pointed out above, however, this is notgenerally of importance since the zipper will be finally used with aparticular face exposed.

Reference has been made above to the fact that the compression ordistortion of the zipper elements may be carried out to such extent thatgood conductivity between adjacent zipper elements might not exist whenthe zipper is straight but only when it has a radius of curvatureimparted thereto. It will be evident that if the lesser distortion ofthis type is provided, it is desirable that in the bath the zippershould have imparted to it a suitable radius of curvature, and this maybe imparted as indicated by the curvature of the plate 40 or by feedingthe zipper about a cylindrical surface which will impart a still smallerbut suitable radius of curvature thereto to insure good conductivitybetween the elements. In general, it may be stated that, with sufilcientcompression or distortion (though actually slight) the zipper may bemade continuously conductive even when straight; with less compressionor distortion curvature less than some maxi mum will be required forcontinuous conductivity, the maximum depending upon the amount ofcompression or distortion and, of course, the initial spacing and formof the zipper elements. The compression or distortion required for aparticular zipper to cause it to become continuously conductive under aparticular radius of curvature may be readily ascertained by trial.

It will also be evident that the zipper as originally manufactured mayhave its elements suitably formed and tightly assembled, i. c. moreclosely arranged along the tapes than usual, so that continuity ofconductivity will occur when the closed zipper is either straight orconformed to a suitable curvature by contact with a conductive surfaceover which it moves in the electrolyte.

The broad aspects of the disclosure herein are claimed in my applicationSerial Number 301,510, filed of even date herewith.

What is claimed is:

1. A method for the electrolytic treatment of a slide fastener of thezipper type having metallic interengaging elements comprising subjectingthe elements of the closed zipper to compression to distort the shape ofindividual elements to reduce clearances between adjacent interengagingelements thereof and then progressing the closed zipper through anelectrolytic bath while causing it to conform to a curvature such thatelectrical continuity is enforced between the interengaging elementsthereof and While at least some elements thereof are in conductivecontact with a member carrying current for the treatment.

2. A method for the electrolytic treatment of a slide fastener of thezipper type having metallic interengaging elements comprising subjectingthe elements of the closed zipper to compression to distort the shape ofindividual elements to reduce clearances between adjacent interengagingelements thereof and then progressing the closed zipper through anelectrolytic bath While curvature is imparted thereto by scrapingcontact of at least some of the elements thereof over a curved membercarrying current for treatment such that electrical continuity isenforced between interengaging elements thereof and References Cited inthe file of this patent UNITED STATES PATENTS 5 Cowper-Coles Nov. 11,1924 Brockway May 5, 1931 Levy et a1. Mar. 27, 1934 Thomas et a1. Aug.10, 1942 10 8 Wooters Nov. 9, 1943 Miller Nov. 30, 1948 Mikulas Aug. 8,1950 Cohn Oct. 30, 1951 Berman et a1. Apr. 1, 1952 FOREIGN PATENTS GreatBritain of 1897 Switzerland Sept. 1, 1949

1. A METHOD FOR THE ELECTROLYTIC TREATMENT OF A SLIDE FASTENER OF THEZIPPE TYPE HAVING METALLIC INTERENGAGING ELEMENTS COMPRISING SUBJECTINGTHE ELEMENTS OF THE CLOSED ZIPPER TO COMPRESSION TO DISTORT THE SHAPE OFINDIVIDUAL ELEMENTS TO REDUCE CLEARANCES BETWEEN ADJACENT INTERENGAGEINGELEMENTS THEREOF AND THEN PROGRESSING THE CLOSED ZIPPER THROUGH ANELECTROLYTIC BATH WHILE CAUSING IT TO CONFORM TO A CURVATURE SUCH THATELECTICAL CONTINUITY IS ENFORCED BETWEEN THE NTERENGAGING ELEMENTSTHEREOF AND WHILE AT LEAST SOME ELEMENTS THEREOF ARE IN CONDUCTIVECONTACT WITH A MEMBER CARRYING CURRENT FOR THE TREATMENT.